A COMPARISON OF WATER JET, ABRASIVE JET AND ROTARY DIAMOND DRILLING IN HARD ROCK

Construction activities which require the placement of utilities in hard rock would benefit from a lightweight system which is capable of accurately drilling a short constant radius arc as illustrated in Figure 1. Existing mechanical drilling systems are capable of drilling shallow directional holes but the equipment is heavy, drilling rates are low and costs are high. A comparison of approaches for rapidly drilling a small-diameter (25-50-mm), near-surface, hole through a short-radius (30-m) arc in a variety of hard rock types is provided here. Four approaches were considered: